My opinion is that there should NOT be new variables created due to missing value imputation. The original variable names are well enough. The process should only impute the new values in place of the missing values for these variables, and NOT create ‘IMP_’- variables,
From analyst point of view, there is no need on having BOTH variables included within your analysis; i.e. imputed and non-imputed values. You always use only one of theses two.